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Discussion Starter · #1 ·
I've been having issues with the 3ph on my MF1655. It works strong until she is nice and warm. About a half hour of use,it won't pick up the implement. I've checked the fluid before and it's up. But tonight I thought I'd check it again. Have some work for it tomorrow. When I unscrewed the dipstick,there was a gush of air released. So my question is, is there a vent in the rear-end?
 

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It only takes a tiny hole to vent the hydro. 1/16" diameter will do it. The vent was plugged on one of my trractors and the previous owner had filled the transmission to the top of the fill tube??. When I opened the cap to check the fluid level it shot out about a foot in the air. If the vent is plugged it can also cause fluid to be forced out the weakest point. In my case it was the axle seals. If you leave the cap loose or loosen it to relieve pressure then restart and test the 3Pt lift that should tell you if the lack of venting is the problem. Are those hydros belt driven on a 1655. If so, you might want to check to make sure the hydro is being turned at full speed. Could be a loose pulley/key etc.
 

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Discussion Starter · #6 ·
The dipstick cap is supposed to be vented.

Either the seals are worn in the 3PH cylinder, or the valve body is worn. Seals are cheaper than a fresh valve.
I was thinker the valve too,but it workss great when cold
 

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Discussion Starter · #7 ·
It only takes a tiny hole to vent the hydro. 1/16" diameter will do it. The vent was plugged on one of my trractors and the previous owner had filled the transmission to the top of the fill tube??. When I opened the cap to check the fluid level it shot out about a foot in the air. If the vent is plugged it can also cause fluid to be forced out the weakest point. In my case it was the axle seals. If you leave the cap loose or loosen it to relieve pressure then restart and test the 3Pt lift that should tell you if the lack of venting is the problem. Are those hydros belt driven on a 1655. If so, you might want to check to make sure the hydro is being turned at full speed. Could be a loose pulley/key etc.
Thanks Brian,i will let it warm up,and loosen cap and see what happens. And yes the hydro is ran off belts on these.
 

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Red Tractor Nut & Diesel Addict
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If the 3pt holds implement up after a while without dropping then cylinder piston seals are okay. On one of my sundstrand units, it did just like yours and turned out to be a blown o-ring between pump and motor body. A 5 cent part! This seal was blown just enough to hold thick cooler oil, but when the oil heated, it would dump the oil right back into the open inside of the unit. It didn't affect my hydrostatic at all. Is yours Eaton (round finned unit) or Sundstrand? I know almost nothing about the Eaton units.
 

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This is not a fix, but on worn, older stuff that just has natural wear, Lucas Hydraulic Oil Booster & Stop Leak, works wonders. It's not a mechanical repair, but if slight seal wear is present, it will greatly improve the performance. I usually change the fluid and filter and replace 20%-25% with the Lucas.
 

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Discussion Starter · #10 ·
Daniel, mine is the Eaton. It does not hold the implement up after you shut it off. And it does creep down while running,but not as fast as when it's off. And no there is no difference in my hydrostatic either. Do you have a diagram of this seal that you mentioned ?
 

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Discussion Starter · #11 ·
This is not a fix, but on worn, older stuff that just has natural wear, Lucas Hydraulic Oil Booster & Stop Leak, works wonders. It's not a mechanical repair, but if slight seal wear is present, it will greatly improve the performance. I usually change the fluid and filter and replace 20%-25% with the Lucas.
Thanks, im going to try the cap first.then,if that don't work,maybe change out the oil and filter and add some Lucas. It's been used for about a year and a half now since I changed it last. And this tractor gets a lot of use.
 

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Red Tractor Nut & Diesel Addict
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Daniel, mine is the Eaton. It does not hold the implement up after you shut it off. And it does creep down while running,but not as fast as when it's off. And no there is no difference in my hydrostatic either. Do you have a diagram of this seal that you mentioned ?
Then it does sound like your cylinder piston seal is worn, and/or a worn valve body letting fluid leak back into the return line port. Likely it's just the cylinder needing rebuilt, which is simple and easy to do yourself.
 

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Discussion Starter · #13 ·
Thanks Daniel is there a kit avalible still? Or is it cheaper to pull it apart and take the seals to a hydraulic shop and just match up the o-rings?
 

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If you need a breakdown for the valves, the Sears FF's use the same valve. Here's a pic of those.
[sharedmedia=core:attachments:156875] Font Parallel Number Document
 

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Red Tractor Nut & Diesel Addict
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Thanks Daniel is there a kit avalible still? Or is it cheaper to pull it apart and take the seals to a hydraulic shop and just match up the o-rings?
I would just go match them up at a hydraulic shop. Usually MUCH cheaper & same stuff.
 

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Discussion Starter · #16 ·
Thanks Kenny,hope it's not my valves but if so,this will come in handy.
 

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Discussion Starter · #17 ·
Ok so if it ain't the cap plugged I will tear the cylinder apart and reseal it. Change fluid and filter and ad some lucas,just as a precaution. Thanks guys. I will update when I find something new out.
 

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Thanks Kenny,hope it's not my valves but if so,this will come in handy.
It's always nice to see what is inside there. Most likely the cylinder, but you never know!
 

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Along with all the other bits and pieces, there is also an o-ring between the piston and the rod.

Do a little judicious cleanup of the base end of the cylinder. The piston comes out there, not the head end. Remove the base end fitting before trying to push out the plug.

Who put the Eaton in a MF1655? The Snappers came with Eatons, the MF's came with Sundstrands.
 
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